Idaho's water supply outlook near normal

Posted at 3:34 PM, Apr 07, 2016
and last updated 2016-04-07 17:34:45-04

The Natural Resources Conservation Service has released the fourth water supply outlook report for the 2016 water year – and it appears near normal.

Idaho’s mountain snowpack ranges from 95 to 125% of normal for most of the state, officials said. The lowest snowpacks are 67% and 76% of median in the Owyhee and Palouse basins, because the snow in these basins is nearly melted -- except in the higher elevations.

Currently, reservoir storage is in good shape across most of the state, according to the NRCS; with storage releases currently being made on the Boise reservoir system. Elsewhere, reservoir storage levels are starting to increase with the mid-elevation snow now starting to melt.

“Above-normal March precipitation across the state put the icing on the cake in terms of providing adequate streamflows this year,” said Ron Abramovich, water supply specialist with the Natural Resources Conservation Service. “It was just what we needed to nearly guarantee this year’s water supply for the numerous users across the state.”

Also, temperatures at higher elevations were cold enough to allow most of the moisture to fall as snow -- which added more water to the mountainous snowpack to melt later this spring. In the lower elevations, the March rains were very beneficial by increasing soil moisture, improving rangeland conditions and generating lower elevation streamflow across the state.

Current streamflow forecasts are near normal across the state, between 90 to 115% of average. The exceptions are the South Hills drainages (Oakley and Salmon Falls) which are forecast at about 135% of normal while the Bear River at Stewart Dam is only forecast at 69% of average due to upstream diversions. The Snake River near Heise is forecast at 96% of average and should provide adequate irrigation supplies for the Magic Valley water users.

“The final piece of the water supply picture is spring precipitation,” said Abramovich. “As we have learned in the past, spring precipitation can make or break our streamflow forecasts. More precipitation is still needed this spring.”